Re: Do we still need constraint_exclusion? - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Do we still need constraint_exclusion?
Date
Msg-id 6731.1231368361@sss.pgh.pa.us
Whole thread Raw
In response to Re: Do we still need constraint_exclusion?  (Bruce Momjian <bruce@momjian.us>)
Responses Re: Do we still need constraint_exclusion?  (Simon Riggs <simon@2ndQuadrant.com>)
Re: Do we still need constraint_exclusion?  ("Jaime Casanova" <jcasanov@systemguards.com.ec>)
List pgsql-hackers
Bruce Momjian <bruce@momjian.us> writes:
>> * Simon Riggs (simon@2ndQuadrant.com) wrote:
>>> I don't really understand this. Who can set up an inherited table
>>> structure but can't remember to turn on constraint_exclusion?

> This new change also adds the constraint exclusion overhead only for
> inhertance (by default) so it should slightly improve query peformance.

Right, I think that's the real winning argument for having this: it
gets the benefit of c_e for partitioned tables without imposing overhead
for non-partitioned tables.  See Josh B's remarks upthread about
actually going to the trouble of turning c_e off and on on-the-fly to
try to approximate that result.
        regards, tom lane


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